The invention relates generally to power supplies, and more particularly to cascaded power converters.
Cascaded power converter arrangements including two or more power converters are well known. The cascaded arrangement of conventional converter topologies is dependent upon the requirements of a particular application. Cascaded converters are most commonly used to provide large input to output voltage conversion ratios (step-up or step-down) or for providing multiple functions that are not feasibly implemented in a single converter.
In one conventional cascaded arrangement, a first buck converter is followed by a second buck converter. A buck converter is characterized by its voltage step-down ratio wherein the output voltage is lower than the input voltage to thereby produce a higher average output current. The cascaded buck converters produce an even larger voltage step-down ratio and a correspondingly greater average output current.
Another known arrangement utilizes cascaded boost PFC converters. A boost converter is characterized by its voltage step-up ratio wherein the output voltage is higher than the input voltage but produces a lower average output current. The cascaded boost converters produce an even larger voltage step-up ratio and a correspondingly smaller average output current.
In yet another known arrangement, a non-isolated boost converter is followed by one of several possible post regulator circuits, such as a buck or isolated buck derived converter, to provide for independently regulated auxiliary output voltages in single or multiple output converters.
With the proliferation of new semiconductor device families, the number of different supply voltages needed to power data communication and telecommunication systems has increased significantly. These supply voltages must also be generated at ever increasing current ratings, stringent output voltage tolerances, and fast transient responses. Conventional cascaded converters can be inadequate for systems with these requirements. Therefore, a new approach in power conversion and distribution is needed.